The role of a dishwashing composition is twofold: to clean soiled dishware and to leave it shiny. Typically, when water dries from surfaces water-marks, smears and/or spots are left behind. These water-marks may be due to the evaporation of water from the surface leaving behind deposits of minerals which were present as dissolved solids in the water, for example calcium, magnesium and sodium ions and salts thereof or may be deposits of water-carried soils, or even remnants from the cleaning product, for example soap scum. During the course of this work, it has been observed that this problem can be often exacerbated by some cleaning compositions which modify the surface of the dishware during the automatic dishwashing process in such a way that after rinsing, water forms discrete droplets or beads of water remain on the surface instead of draining off. These droplets or beads dry to leave noticeable spots or marks known as water-marks. This problem is particularly apparent on ceramic, stainless steel, plastic, glass and painted surfaces.
When items are washed in an automatic dishwasher it is important to the consumer that those items come out at the end of the cycle as clean as possible. An item is clean to the consumer if there are no visible pieces of soil or hard water deposits. This means no films, spots, grit or residues of anything. It is also as important that when the consumer touches the items they do not feel anything other than the clean surface of item. When an item is not clean, a consumer may feel either a rough and gritty surface or they may feel a greasy surface.
A rough and gritty surface can be produced when hard water deposits, i.e. calcium carbonate and other salts deposit on the item. This can be accentuated if there are food soils mixed in with the deposits. A greasy surface can be produced if excess greases and fat soils from the wash liquor of the dishwashing process have been deposited onto the item. Whether rough and gritty or greasy, these feelings are unpleasant for the consumer and indicate that the items which they have washed are not clean.
The object of the present invention is to provide a dishwashing composition that leaves the washed dishware clean with reduced incidence or spots.